Featured with small size, high efficiency and long service life, light emitting diode is widely used in fields like traffic light and outdoor full color display and is becoming a study hot point in electronics field.
To get high-luminance LED, the key is to improve the internal and external quantum efficiency. The light extraction efficiency of chip is a main factor constraining the external quantum efficiency. As the refractive indices of epitaxial material, substrate material and air differ a lot, the light produced at the light emitting layer will be totally reflected at the material interfaces with different refractive indices and cannot be exported from the chip. Therefore, study on improving light emitting efficiency of LED is active, mainly including: change of chip's geometric profile, use of inverted pyramid structure, resonant cavity or photonic crystal. It can be seen that chip structure design is of great importance to improve the light-emitting efficiency of LED.
Chinese Patent Application No. 200910037641.3 discloses a light emitting diode with current blocking layer, comprising a substrate, an N-type semiconductor material layer formed on the front side of the substrate, a light emitting layer formed on the N-type semiconductor material layer, a P-type semiconductor material layer formed on the light emitting layer, a transparent electrode layer formed on the P-type semiconductor material layer, an anode metal electrode bonding line layer formed on the transparent electrode layer and a cathode metal electrode bonding line layer formed on the N-type semiconductor material layer, bonding lines formed on the anode metal electrode bonding line layer and the cathode metal electrode bonding line layer, and a current blocking layer at the local position under the anode metal electrode bonding line layer and between the transparent electrode layer and the P-type semiconductor material layer.